ANALYTE DETECTOR FOR DETECTING AT LEAST ONE ANALYTE IN AT LEAST ONE FLUID SAMPLE
An analyte detector for detecting at least one analyte in at least one fluid sample is proposed. The analyte detector comprises at least one multipurpose electrode exposable to the fluid sample. The analyte detector further comprises at least one field-effect transistor in electrical contact with the at least one multipurpose electrode. The analyte detector further comprises at least one electro-chemical measurement device configured for performing at least one electrochemical measurement using the multipurpose electrode.
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This application is a continuation of International Patent Application No. PCT/EP2018/054282, filed 21 Feb. 2018, which claims the benefit of European Patent Application No. 17157374.4, filed 22 Feb. 2017, the disclosures of which are hereby incorporated herein by reference in their entirety.
TECHNICAL FIELDThe present disclosure relates to an analyte detector and a method for detecting at least one analyte in at least one fluid sample. The disclosure further relates to the use of the analyte detector for the qualitative and/or quantitative determination of the at least one analyte in a fluid. The devices and methods of the present disclosure, as an example, may be used for diagnostic purposes, e.g., in clinical or laboratory analytics or for home monitoring purposes. The devices and methods of the present disclosure specifically may be used for detecting one or more analytes in body fluids or other liquids. As an example, DNA detection may be named. Other applications and uses, however, are feasible.
BACKGROUNDA wide variety of analyte detectors for detecting at least one analyte in at least one fluid sample have been described. Analyte detectors configured for reliably detecting chemical and/or biological species in a qualitative and/or quantitative manner can be used for various purposes such as, but not limited to, diagnostic purposes, monitoring of environmental contamination, food safety evaluation, quality control or manufacturing processes. Such analyte detectors may for instance rely on transistor-based measurements for identifying the at least one analyte. Transistor-based analyte detectors have been adapted to allow the detection of a wide range of analytes including biomolecules such as proteins, antibodies, antigens, DNA, and chemical species such as ionic species and electrolytes.
A number of studies describe the use of transistor-based analyte detectors in the identification of antigens, antibodies or other proteins: Elnathan et al. (Elnathan et al., Nano Lett. 2012, 12, 5245-5254) describe the detection of proteins in untreated serum and blood samples in the sub-pM concentration range using a nanowire-based field-effect transistor (FET) device combined with size-reduced antibody fragments. The use of size-reduced antibody fragments permits the biorecognition event to occur in closer proximity to the nanowire surface, falling within the charge-sensitive Debye screening length. In a study published by Gao et al. (Gao et al., Nano Lett. 2015, 15, 2143-2148) incorporation of a porous and biomolecule permeable layer on a FET-based nanoelectric sensor is described. The polymer layer increases the effective screening length in the region immediately adjacent to the FET-based sensor surface and thereby enables the detection of biomolecules in high ionic strength solutions in real-time. The same study also reports that silicon nanowire field-effect transistors with additional polyethylene glycol (PEG) modification can readily detect prostate specific antigen (PSA) in solutions with phosphate buffer concentrations as high as 150 mM. Kim et al. (Kim et al., Biosens Bioelectron. 2009 Jul15;24(11):3372-8) present a simple and sensitive method for real-time detection of a prostate cancer marker (PSA-ACT complex) through label-free protein biosensors based on a carbon nanotube field-effect transistor (CNT-FET). Tarasov et al. (Tarasov et al., 2D Mater. 2 (2015) 044008) use gold-coated graphene FETs to measure the binding affinity of a specific protein-antibody interaction. In a different study, Tarasov et al. (Tarasov et al., Biosens Bioelectron. 2016 May 15;79:669-78) employ an extended-gate field-effect transistor for direct potentiometric serological diagnosis using the model pathogen Bovine Herpes Virus-1 (BHV-1). To demonstrate the sensor capabilities as a diagnostic tool, BHV-1 viral protein gE is expressed and immobilized on the sensor surface to serve as a capture antigen for BHV-1-specific antibody (ant-gE). The gE-coated immunosensor was shown to be highly sensitive and selective to anti-gE and significantly faster than Enzyme-Linked ImmunoSorbent Assay (ELISA) that is typically performed by centralized laboratories.
Other studies explore the potential of transistor-based analyte detectors for the identification of nucleic acids, such as DNA or RNA, or possible components thereof, such as adenosinmono-phosphate (AMP). In U.S. Patent Application Publication No. 2010/0053624 A1 a biosensor is disclosed that can convert biological interactions into electrical and optical signals to sense a material to be analyzed. The biosensor includes a substrate, a source electrode and a drain electrode formed on one surface of the substrate, a carbon nanotube connecting the source and the drain electrodes, a metal gate covering the carbon nanotube, a recognition component immobilized on the metal gate, and a passivation layer covering the source and drain electrodes. In one embodiment, the recognition component may be a single-stranded oligonucleotide such as DNA or RNA. In the case of DNA, the biosensor has a recognition DNA immobilized on the surface of the metal gate. Electrical and/or optical signals are generated as a result of hybridization between the recognition DNA and a target DNA. Zayats et al. (Zayats et al., J Am Chem Soc. 2006 Oct 25;128(42):13666-7) present research applying aptamers for the label-free reagent-less analysis of small molecules. They demonstrate that the small substrate-induced separation of a duplex nucleic acid that includes the aptamer strand, on an ion-sensitive field-effect transistor (ISFET) or on an electrode, forms a substrate-aptamer complex that can be electrically characterized. In particular, an amine-functionalized nucleic acid that acts as aptamer was immobilized on the gate surface and further hybridized with a short nucleic acid. The addition of adenosine displaces the short nucleic acid and assembles the aptamer into the hairpin configuration that binds adenosine mono-phosphate (AMP).
Understanding and controlling the behavior of the analyte detector is crucial for its targeted use. Transistor-based analyte detectors can also respond to chemicals species such as ionic species and electrolytes. Tarasov et al. (Tarasov et al. ACS Nano. 2012 Oct 23;6(10):9291-8) use silicon nanowires coated with highly pH-sensitive hafnium oxide (HfO2) and aluminum oxide (Al2O3) in silicon nanowire field-effect transistor to determine their response to changes in the supporting electrolyte concentration. Wipf et al. (Wipf et al., ACS Nano 2013 Jul 23;7(7):5978-83) modify individual nanowires with thin gold films as a novel approach to surface functionalization for the specific detection of electrolyte ions by ion-sensitive field-effect transistors in a differential set-up. They find that a functional self-assembled monolayer does not affect the unspecific response of gold to pH and background ionic species, which represents a clear advantage of gold compared to oxide surfaces.
Thus, transistor-based analyte detectors have been adapted in numerous ways to detect a multitude of analytes. The advances established in the field of transistor-based analyte detectors are in part due to advances in surface functionalization techniques, in particular those applicable to nano-devices. Shim et al. (Shim et al., Nano Letters 2002 Vol.2, No.4, 285-8) study the adsorption behavior of proteins on the side of single-walled carbon nanotubes. They report that the functionalization of single-walled carbon nanotubes by co-adsorption of a surfactant and polyethylene glycol is found to be effective in resisting non-specific adsorption of streptavidin. In U.S. Pat. No. 7,491,496 B2 a method is disclosed for immobilizing nucleic acid and a method for manufacturing a biosensor using the same method. The method provided enables high-density absorption when immobilizing nucleic acid probes onto a solid support by suppressing electrostatic repulsion among the nucleic acids. A nucleic acid immobilization method to immobilize a nucleic acid onto a solid support, includes: preparing a solution containing a probe molecule which includes a nucleic acid, a spacer molecule, and at least one kind of a divalent cation; and contacting the solution with the solid support for incubation. Yoshimoto et al. (Yoshimoto et al., J Am Chem Soc. 2010 Jun 16; 132(23):7982-9) examine the adsorption behavior of antibody fragments directly immobilized on a gold surface through S-Au linkage. They report that the conformational and/or orientation change of antibody fragments was suppressed by a coimmobilized mixed polyethylene glycol layer. Yoshimoto et al. expect their findings to be useful for the improvement of the antibody fragment method and, thus, for the construction of high-performance immunosensor surfaces.
However, analyte detectors able to detect at least one analyte in at least one fluid sample may also be based on electrochemical measurements. For details of electrochemical test elements and potential test chemicals useful in such test elements, which may also be used within the present disclosure, reference may be made to J. Hoenes et al.: The Technology Behind Glucose Meters: Test Strips, Diabetes Technology & Therapeutics, Vol. 10, Supplement 1, 2008, S-10 to S-26. Further, impedance biosensors are a class of electrical biosensors able to detect unlabeled DNA and protein targets by monitoring changes in surface impedance when a target molecule binds to an immobilized probe. The challenges caused by the affinity capture step and other challenges unique to impedance readout are discussed in Daniels and Pourmand, Electroanalysis, 2007 May 16, 19(12): 1239-1257. Furthermore, in their fundamental study from 1958, Severinghaus and Bradley (Severinghaus and Bradley, J Appl Physiol. 1958 Nov:13(3):515-20) describe an apparatus to permit rapid and accurate analysis of oxygen and carbon dioxide tensions in gas, blood or any liquid mixture using an oxygen electrode and a carbon dioxide electrode. Wu et al. (Wu et al., Sensors and Actuators B 110 (2005) 342-9) report on a miniature Clark-type oxygen sensor that has been integrated with a microstructure using a novel fabrication technique. Moreover, analyte detectors may also combine functional elements as reported by Zhu et al. (Zhu et al., Nano Lett. 2014 Oct 8;14(10):5641-9), who present a graphene enabled, integrated optoelectro-mechanical device and demonstrate its utility for biomolecular sensing. They demonstrate a novel nanoscale sensing device with optical, electronic and mechanical functional elements integrated on the same chip. By having each element target a different concentration regime, the sensitivity-dynamic range trade-off of traditional single-mode sensors can be significantly mitigated.
International Patent Application Publication No. WO 2016/173542 A1 discloses a system for detecting a target and a method for detecting a target. The system includes a field effect transistor, having a gate, a source, and a drain; a potentiostat, having a working electrode, a counter electrode, and a reference electrode; wherein the working electrode is coupled with a detection region, and the counter electrode is coupled with the gate; wherein the detection region, the gate, and the reference electrode are arranged in an ion fluid; wherein the potentiostat is configured to generate redox in the ion fluid by an electrochemical method to detect the target.
Formisano et al.: “Inexpensive and fast pathogenic bacteria screening using field-effect transistors”. BIOSENSORS AND BIOELECTRONICS, ELSEVIER BV, NL, vol. 85, 21 April 2016 (2016-04-21), pages 103-109, XP029680551, ISSN: 0956-5663, DOI: 10.1016/J.BIOS.2016.04.063, describes a label-free sensor for fast bacterial detection based on metal-oxide-semiconductor field-effect transistors (MOSFETs). The electrical charge of bacteria binding to the glycosylated gates of a MOSFET enables quantification in a straightforward manner and at a higher sensitivity than is achieved with electrochemical impedance spectroscopy (EIS) and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy (MALDI-ToF) on the same modified surfaces.
Vieira et al.: “Label-free electrical recognition of a dengue virus protein using the SEGFET simplified measurement system”. Analytical Methods, vol 6, no.22, 8 September 2014 (2014-09-08), pages 8882-8885, XP055360591, GBR ISSN: 1759-9660, DOI: 10:1039/C4AY01803F, describes the use of a separative extended gate field-effect transistor (SEGFET) as an immunosensor for the label-free recognition of dengue virus nonstructural protein 1 (NS1). NS1 is detected in a concentration range of 0.25 to 5.0 μg mL-1, indicating that the system is promising for the early and simple diagnosis of dengue.
U.S. Patent Application Publication No. 2016/0131613 A1 discloses a floating gate based sensor apparatus including at least two separate electrical bias components with respect to a floating gate based sensor surface within the floating gate based sensor apparatus. By including the at least two electrical bias components, the floating gate based sensor apparatus provides enhanced capabilities for biomaterial and non-biomaterial detection and manipulation while using the floating gate based sensor apparatus.
Lin et al.: “Non-Faradaic electrical impedimetric investigation of the interfacial effects of neuronal cell growth and differentiation on silicon nanowire transistors”. ACS APPLIED MATERIALS AND INTERFACES, vol. 7, no.18, 13 May 2015 (2015-05-13), pages 9866-9878, XP055360704, US ISSN: 1944-8244, DOI: 10.1021/acsami.5b01878, describes the application of silicon nanowire field-effect transistors (SiNWFET) devices for noninvasive, real-time monitoring of interfacial effects during cell growth and differentiation using cultured rat adrenal pheochromocytoma (PC12) cells. Monitoring of cell adhesion during growth and morphological changes during neuronal differentiation was performed by measuring the non-Faradaic electrical impedance of the cell-SiNW FET system using a precision LCR meter. Zhan et al.: “Graphene field-effect transistor and its application for electric sensing”. SMALL, 7 July 2014 (2014-07-07), XP055200050, ISSN: 1613-6810, DOI: 10.1002/smll.201400463, describes the fabrication and characterization of graphene based field-effect transistors (GFETs) and introduces the new developments in physical, chemical, and biological electronic detection using GFETs. Further, several perspectives and current challenges of GFETs development are presented, and some proposals are suggested for further development and exploration.
U.S. Patent Application Publication No. 2012/0019315 A1 discloses a bio material receiving device including a thin film transistor (TFT) including a drain electrode, and a nano well accommodating a bio material. The drain electrode includes the nano well. The TFT may be a bottom gate TFT or a top gate TFT. A nano well array may include a plurality of bio material receiving devices. In a method of operating the bio material receiving device, each of the bio material receiving devices may be individually selected in the nano well array. When the bio material is accommodated in the selected bio material receiving device, a voltage is applied so that another bio material is not accommodated.
Arquint et al.: “Integrated blood-gas sensor for pO2, pCO2 and pH” SENSORS AND ACTUATORS B: CHEMICAL: INTERNATIONAL JOURNAL DEVOTED TO RESEARCH AND DEVELOPMENT OF PHYSICAL AND CHEMICAL TRANSDUCERS, ELSEVIER BV, NL, vol. 13, no. 1-3, 1 May 1993 (1993-05-01), pages 340-344, XP026588341, ISSN: 0925-4005, DOI: 10.1016/0925-4005(93)85396-R [retrieved on 1993-05-01], describes the fabrication and characterization of a combined pO2, pCO2 and pH chemical sensor, designed for blood gas monitoring. Classical electrochemical principles are used in a miniaturized planar-type structure. Both amperometric (pO2) and potentiometric devices (pCO2, pH) are integrated on a 10 mm×10 mm chip. The transducer part of the chip is realized using standard silicon technology. Poly-acrylamide and polysiloxane layers, which are used as hydrogel and gas-permeable membrane, respectively, are deposited and patterned by photopolymerization. Thus, the whole sensor is fabricated on wafer level using IC-compatible processes. The characterization has been performed in aqueous solutions and in blood used for transfusion. For this purpose, the chip is mounted into a flow-through cell.
Gutiérrez-Sanz et al.: “Direct, label-free, and rapid transistor-based immunodetection in whole serum” ACS SENSORS 2017 Sep 22;2(9), pages 1278-1286, DOI: 10.1021/acssensors.7b00187, Epub 2017 Aug 30, describes how tailoring the sensing surface of a transistor-based biosensor with short specific biological receptors and a polymer polyethylene glycol (PEG) can strongly enhance the sensor response. In addition, the sensor performance can be dramatically improved if the measurements are performed at elevated temperatures (37° C. instead of 21° C.). With this novel approach, highly sensitive and selective detection of a representative immunosensing parameter-human thyroid-stimulating hormone-is shown over a wide measuring range with subpicomolar detection limits in whole serum. This allows direct immunodetection in whole serum using transistor-based biosensors, without the need for sample pretreatment, labeling, or washing steps. The presented sensor is low-cost, can be easily integrated into portable diagnostics devices, and offers a competitive performance compared to state-of-the-art central laboratory analyzers.
Filipiak et al.: “Highly sensitive, selective and label-free protein detection in physiological solutions using carbon nanotube transistors with nanobody receptors” Sensors and Actuators B: Chemical, Volume 255, Part 2, February 2018, pages 1507-1516, DOI: 10.1016/j.snb.2017.08.164, describes combining highly stable FETs based on single-walled semiconducting carbon nanotube (SWCNTs) networks with a novel surface functionalization comprising: 1) short nanobody (VHH) receptors, and 2) a polyethylene glycol (PEG) layer. These measures overcome the two major challenges that have limited the use of nanomaterial-based field-effect transistors (FETs) in physiological samples: screening of the analyte charge by electrolyte ions (Debye screening) and non-specific adsorption. Nanobodies are stable, easy-to-produce biological receptors that are very small (˜2-4 nm), thus enabling analyte binding closer to the sensor surface. Despite their unique properties, nanobodies have not been used yet as receptors in FET based biosensors. The addition of PEG strongly enhances the signal in high ionic strength environment. Using green fluorescent protein (GFP) as a model antigen, high selectivity and sub-picomolar detection limit with a dynamic range exceeding 5 orders of magnitude is demonstrated in physiological solutions. In addition, long-term stability measurements reveal a low drift of SWCNTs of 0.05 mV/h. The presented immunoassay is fast, label-free, and does not require any sample pretreatment or washing steps.
In the field of analytics, generally, one major technical challenge typically resides in the selection of appropriate methods and devices for the specific analyte to be detected. Even more, in some cases, several types of analytes in one and the same sample may have to be detected. As discussed above, a wide variety of detectors having differing sensitivities and measurement principles is available. Transistor-based detectors, as an example, are highly sensitive to the analyte charge. Analyte detectors based on electrochemical measurements are usually sensitive to the current, impedance or potential changes resulting from electrochemical reactions involving the analyte. Thus, typically, for each analyte to be detected, a specific detector has to be selected, having properties suited for the analyte. The measurement setup, consequently, typically is highly specific for the analyte to be tested for, and the setup, in total, typically lacks versatility. Further, each measurement principle typically has its own drawbacks, technical limitations and inaccuracies. Consequently, the choice of a measurement principle also implies the choice of the technical drawbacks involved with this measurement principle. A combination of measurement principles, however, typically leads to a complex setup and evaluation. There is, consequently, a general need for electronic sensors in physiological liquids which generally provide a high versatility and selectivity and which provide a more universal sensor layout as compared to the methods, measurement principles and devices known in the art.
BRIEF SUMMARYIt is against the above background that the embodiments of the present disclosure provide certain unobvious advantages and advancements over the prior art. In particular, the inventors have recognized a need for improvements in an analyte detector for detecting at least one analyte in at least one fluid sample.
Although the embodiments of the present disclosure are not limited to specific advantages or functionality, it is noted that the present disclosure provides an analyte detector and a method for detecting at least one analyte in at least one fluid sample which allow for a high versatility, selectivity and sensitivity and, still, which provide a more universal sensor layout as compared to known means and methods.
In accordance with one embodiment of the present disclosure, an analyte detector for detecting at least one analyte in at least one fluid sample is provided, the analyte detector comprising at least one multipurpose electrode exposable to the fluid sample, the analyte detector further comprising at least one field-effect transistor in electrical contact with the at least one multipurpose electrode, the analyte detector further comprising at least one electrochemical measurement device configured for performing at least one electrochemical measurement using the multipurpose electrode, wherein the analyte detector further comprises at least one controller, wherein the controller is connected to the field-effect transistor and to the electrochemical measurement device and wherein the controller is configured for controlling at least one transistor measurement by using the field-effect transistor and wherein the controller additionally is configured for controlling the at least one electrochemical measurement by using the electrochemical measurement device.
In accordance with another embodiment of the present disclosure, a method for detecting at least one analyte in at least one fluid sample is provided, the method using the analyte detector according to an embodiment of the present disclosure, the method comprising the following steps: a) providing at least one multipurpose electrode; b) providing the at least one fluid sample in contact with the multipurpose electrode; c) performing at least one transistor measurement by using at least one field-effect transistor in electrical contact with the at least one multipurpose electrode; and d) performing at least one electrochemical measurement by using the multipurpose electrode.
These and other features and advantages of the embodiments of the present disclosure will be more fully understood from the following description in combination with the drawings and the accompanying claims. It is noted that the scope of the claims is defined by the recitations therein and not by the specific discussion of features and advantages set forth in the present description.
The following detailed description of the embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of the embodiments of the present disclosure.
DETAILED DESCRIPTIONAs used in the following, the terms “have”, “comprise” or “include” or any arbitrary grammatical variations thereof are used in a non-exclusive way. Thus, these terms may both refer to a situation in which, besides the feature introduced by these terms, no further features are present in the entity described in this context and to a situation in which one or more further features are present. As an example, the expressions “A has B”, “A comprises B” and “A includes B” may both refer to a situation in which, besides B, no other element is present in A (i.e., a situation in which
A solely and exclusively consists of B) and to a situation in which, besides B, one or more further elements are present in entity A, such as element C, elements C and D or even further elements.
Further, it shall be noted that the terms “at least one”, “one or more” or similar expressions indicating that a feature or element may be present once or more than once typically will be used only once when introducing the respective feature or element. In the following, in most cases, when referring to the respective feature or element, the expressions “at least one” or “one or more” will not be repeated, notwithstanding the fact that the respective feature or element may be present once or more than once.
Further, as used in the following, the terms “preferably”, “more preferably”, “typically”, “more typically”, “particularly”, “more particularly”, “specifically”, “more specifically” or similar terms are used in conjunction with optional features, without restricting alternative possibilities. Thus, features introduced by these terms are optional features and are not intended to restrict the scope of the claims in any way. Embodiments of the disclosure may, as the skilled person will recognize, be performed by using alternative features. Similarly, features introduced by “in an embodiment of the disclosure” or similar expressions are intended to be optional features, without any restriction regarding alternative embodiments of the disclosure, without any restrictions regarding the scope of the disclosure and without any restriction regarding the possibility of combining the features introduced in such way with other optional or non-optional features of the disclosure.
In accordance with a first embodiment of the present disclosure, an analyte detector for detecting at least one analyte in at least one fluid sample is described. The analyte detector comprises at least one multipurpose electrode exposable to the fluid sample, at least one field-effect transistor in electrical contact with the at least one multipurpose electrode, and at least one electrochemical measurement device configured for performing at least one electrochemical measurement using the multipurpose electrode.
As used herein, the term “analyte detector” may generally refer to an arbitrary device configured for an analytical examination of the sample. The analyte detector may be configured for conducting at least one analysis, such as a medical analysis, of the sample. As generally used within the present disclosure, the terms “analysis”, “analytical examination” and “determination of one or more analytes” are used synonymously and are understood to describe a qualitative and/or a quantitative detection of the at least one analyte. In particular, said terms may be understood as a determination of the concentration or amount of the respective analyte, where the sole determination of the absence or presence of the analyte may also be regarded as an analytical examination. Thus, specifically, the analyte detector may be configured for qualitatively and/or quantitatively detecting one or more analytes, specifically in one or more samples. The detection of the at least one analyte may take place at a high degree of sensitivity.
As further used herein, the term “analyte” generally may refer to an arbitrary chemical or biological substance or species, such as an ion, an atom, a molecule or a chemical compound. The analyte specifically may be an analyte which may be present in a bodily fluid or a body tissue. The term analyte specifically may encompass atoms, ions, molecules and macromolecules, in particular biological macromolecules such as nucleic acids, peptides and proteins, lipids, sugars, such as glucose, and metabolites. Further examples of potential analytes to be detected will be given in further detail below.
As used herein, the term “fluid sample” generally may refer to a liquid or gas. The fluid sample may have a defined or definable volume. Further, the fluid sample may be comprised in a defined or definable space or may also be present in an open space such as in an open surrounding. The fluid sample may be present in a static state or may flow continuously or discontinuously. The fluid sample may, as an example, be a pure liquid or a homogeneous or heterogeneous mixture, such as a dispersion, an emulsion or a suspension. Similarly, for gases, mixtures of gases or even mixtures of gases with liquids or solids may be used.
In particular, the fluid sample can contain atoms, ions, molecules and macromolecules, in particular biological macromolecules such as nucleic acids, peptides and proteins, lipids and metabolites, and also biological cells and cell fragments. Typical fluid samples to be examined are bodily fluids such as blood, plasma, serum, urine, cerebrospinal fluid, lachrymal fluid, cell suspensions, cell supernatants, cell extracts, tissue lysates or such likes. Fluid samples can, however, also be calibration solutions, reference solutions, reagent solutions or solutions containing standardized analyte concentrations, so-called standards.
As used herein, the term “electrode” may generally refer to a functional element configured to perform a current measurement and/or a voltage measurement and/or configured to apply a current and/or an electrical potential and/or a voltage to an element in electrical contact with the electrode. In particular, the electrode may comprise a conducting and/or a semiconducting material. As an example, the electrode may comprise at least one metallic material and/or at least one organic or inorganic semiconducting material, having at least one conducting or semiconducting surface. The surface itself may form the electrode or a part of the electrode. As an example, the electrode may comprise at least one material, specifically at least one surface material, having an electrical conductivity of at least 1,000 S/m, e.g., at least 1,000,000 S/m, either isotropically or anisotropically in at least one direction.
As used herein, the term “in electrical contact” may generally refer to the arrangement or configuration of at least two components, wherein at least one of the components is able to electrically influence the at least one other component and/or to at least partially control an electrical quality of the other component such as, but not limited to, its conductivity and electrical current flow, for instance via field effects. In particular, an electrode may be in electrical contact with an element without being in direct physical contact with said element. Thus, an electrode may control the electrical current flow within an element by application of a voltage despite being insulated from said element. Insulation may, for instance, be constituted by an oxide layer as is typically the case for a gate electrode of a metal oxide semiconductor field-effect transistor (MOSFET), a subgroup of insulated-gate field-effect transistors (IGFET), which is described in more detail below. Thus, generally, for being in electrical contact with each other, the at least two components may be located in close proximity, without being in direct physical contact with one another, such that, however, the components may influence one another electrically. Additionally, or alternatively, however, the at least two components may also be physically connected via at least one connecting element having at least semiconducting properties or electrically conductive properties, such as by at least one electrical conductor. Again, additionally or alternatively, the at least two components may be separate components or may fully or partially be integrated into one another. As an example, the at least one multipurpose electrode may either be connected to the field-effect transistor via at least one connecting element, such as via at least one electrically conductive lead, or may even fully or partially be integrated into the field-effect transistor. Various possibilities are given.
As used herein, the term “multipurpose electrode” may generally refer to an arbitrary electrode configured to be able to form part of at least two different measurement devices. Thus, the multipurpose electrode may take part in analytical examinations based on at least two different methods, wherein each of the methods requires the use of at least one measurement device. The multipurpose electrode may, for instance, be configured to form part of at least both the field-effect transistor and the electrochemical measurement device. Thus, the multipurpose electrode may take part in analytical examinations based on at least one of the methods comprising the use of the field-effect transistor and the at least one other method comprising the use of the electro-chemical measurement device.
As further used herein, the term “exposable” generally refers to the property of an element of providing at least one surface which may be brought into contact with the at least one substance to which the element is to be exposed. Thus, as an example, the at least one multipurpose electrode may provide at least one electrode surface accessible to the fluid sample. Specifically, as will be explained by exemplary embodiments below, the analyte detector may comprise at least one fluid channel, such as a fluid channel having an inlet port and an outlet port, through which the fluid sample may flow, wherein the at least one multipurpose electrode comprises at least one electrode surface accessible from the fluid channel, such that liquid flowing through or present in the fluid channel contacts the at least one electrode surface. Other options, however, are feasible.
As further used herein, the term “field-effect transistor” may generally refer to a functional element comprising at least one source electrode, at least one drain electrode and at least one gate electrode. The field-effect transistor further comprises at least one channel. As used herein, the term “channel” of the field-effect transistor may generally refer to a component able to conduct a current between the source electrode and the drain electrode. The channel may have at least one semiconducting material and/or at least one doped semiconducting material. The semiconducting material may be or may comprise at least one of an inorganic semiconducting material and an organic semiconducting material. Typically, a semiconducting material exhibits an electrical conductivity σ of 10−8 S/cm<σ<104 S/cm. In the field of organic semiconductors, however, due to the impact of the low charge carrier mobilities, due to the molecular orbitals and/or due to the low charge carrier densities, however, this description is often not fully applicable. Thus, organic conductive materials are often denoted as organic semiconductors, even though their conductivity may be higher than 104 S/cm, such as graphene.
In particular, the semiconducting material may comprise one, two or more regions, typically two to ten regions, more typically three regions, wherein each region may be n-type doped or p-type doped. Specifically, the semiconducting material may comprise an inorganic and/or organic semiconducting material. The channel may be able to conduct a current between the source electrode and the drain electrode only under specific external conditions. The conditions may include a temperature of the channel and/or the voltage or electrical potential applied to the channel either directly or via the gate electrode or via an external electrode. In particular, the channel may be constituted by at least one semiconducting material, such as by at least one semiconducting layer. As an example, inorganic and/or organic semiconducting materials may be used. In the following, as a specific example, graphene is used as a semiconducting material, such as by using one or more graphene layers. The gate electrode may be in direct physical contact with the channel. In this configuration the field-effect transistor may generally be referred to as “non-insulated-gate field-effect transistor” (NIGFET). In particular, the gate electrode may be at least partially identical with the channel. Alternatively, the gate electrode may be in indirect physical contact with the channel, e.g., by using one or more electrically insulating materials interposed in between the gate electrode and the channel. In this configuration the transistor may generally be referred to as “insulated-gate field-effect transistor” (IGFET).
The insulated-gate field-effect transistor may be implemented as a “metal-insulator-semiconductor field-effect transistor” (MISFET). In this case, the gate electrode which may comprise at least one metal may be insulated from the channel which may comprise at least one semiconducting material. Specifically, the insulation of the gate electrode from the channel may be constituted by an oxide. In this configuration the field-effect transistor may generally be referred to as “metal-oxide-semiconductor field-effect transistor” (MOSFET). However, other materials for insulation of the gate electrode are feasible. The channel of the field-effect transistor may be in physical contact with an electrolyte solution, which may constitute or form part of the gate electrode. In this configuration an ionic double layer may form, that may serve as insulation of the gate electrode from the channel. In this configuration the field-effect transistor may be referred to as a “solution-gated or liquid-gated FET”. The electrolyte solution may comprise substances that may influence the potential applied to the channel upon close proximity or adsorption to the channel and/or the insulation of the channel, thus allowing the detection of chemical species. In this configuration the field-effect transistor may be referred to as a “chemical field-effect transistor” or ChemFET. In particular, a ChemFET may be configured for the detection of ionic species forming an “ion-sensitive field-effect transistor” (ISFET) that may be sensitive to H+ and/or other ionic species. A layer sensitive to ionic species, such as Al2O3, Si3N4 or Ta2O5, may be in contact with the channel or may form part of the gate electrode of the ISFET and/or may form part of the channel and the gate electrode. In another configuration, the ChemFET may comprise a layer of immobilized enzymes as part of the gate electrode and/or the channel of the field-effect transistor. In this configuration the field-effect transistor may be referred to as an “enzyme field-effect transistor” (ENFET). Binding of the enzyme to the analyte may affect the potential applied to the channel and allow detection of the analyte. Thus, the ENFET is an example of a field-effect transistor-based biosensor (BioFET). As a BioFET the field-effect transistor may comprise a layer of immobilized biomolecules as biorecognition elements able to bind one or more species of molecules, specifically biomolecules, where the binding reaction may either directly or indirectly affect the potential applied to the channel.
The field-effect transistor may further be implemented as an “extended-gate field-effect transistor”. As used herein, the term “extended-gate field-effect transistor” may generally refer to a field-effect transistor comprising a gate electrode configured to allow a spatial separation of the channel of the field-effect transistor from a process or reaction that sets or affects the potential of the gate electrode. Such an electrode may generally be referred to as an “extended gate electrode”. Thus, the extended gate electrode of an extended-gate field-effect transistor may allow to physically separate the process of applying a potential to the channel and the process of applying a potential to the gate electrode.
The at least one field-effect transistor may comprise at least one substrate. The substrate may have purely mechanical properties and function, such as for carrying the above-mentioned components of the field-effect transistor. Alternatively, however, the substrate may also be fully or partially identical with one or more of the above-mentioned components. Thus, as an example, the at least one channel may fully or partially be embodied within the substrate.
The at least one field-effect transistor may further have at least one sensing surface. The at least one sensing surface, as an example, may be a surface of the field-effect transistor which may be exposed to the fluid sample. The sensing surface, as an example, may be a surface of the multi-purpose electrode, e.g., the above-mentioned electrode surface. The sensing surface, however, may also be or comprise another surface, such as a surface of the channel of the field-effect transistor. Various embodiments are feasible and will be described in an exemplary fashion in further detail below.
As used herein, the term “electrochemical measurement” may generally refer to the measurement of at least one measureable characteristic of a redox reaction. The electrochemical measurement and/or the measurable characteristic of the redox reaction, as an example, may imply an electrical current, a voltage, an electrical potential, a mass, for instance a mass deposited on an electrode, an impedance, particularly the real part and/or the imaginary part of the impedance, a capacitance, a resistance or a phase shift. Specifically, the electrochemical measurement may be performed in the presence of an electroactive species. As used herein, the term “electroactive species” may generally refer to a compound that facilitates or enhances or catalyzes the redox reaction, for instance by facilitating an electron transfer. The electroactive species may be dissolved in the fluid sample and/or may be immobilized on a surface of the analyte detector, wherein the surface may be exposable to the fluid sample. In particular, the surface may be the above-mentioned sensing surface and/or the above-mentioned surface of the multipurpose electrode. Typical examples of electroactive species are redox mediators, specifically redox couples, such as but not limited to: potassium ferricyanid/potassium ferrocyanide; hexaammineruthenium (II) chloride/hexaammineruthenium (III) chloride; ferrocene methanol. Further typical examples of electroactive species are reducing agents such as but not limited to ascorbic acid, glutathione, lipoic acid, uric acid, oxalic acid, tannins and phytic acid. The electroactive species may facilitate or enhance the measurement of the at least one measurable characteristic of the redox reaction. As used herein, the term electrochemical measurement device may generally refer to an arbitrary device configured to perform at least one electrochemical measurement.
The term “electrochemical measurement device” may generally refer to an arbitrary device configured for performing at least one electrochemical measurement. For this purpose, as will be outlined in further detail and in an exemplary fashion below, the at least one electrochemical measurement device may comprise one or more electrical devices configured for performing the at least one electrochemical measurement. As an example, the electrochemical measurement device may comprise at least one electrical source, such as at least one electrical source selected from the group consisting of: a constant voltage source, a variable voltage source, a constant electrical current source, a variable electrical current source, a frequency generator for generating periodic electrical signals. Further, the electrochemical measurement device may comprise at least one electrical measurement device configured for measuring at least one electrical signal or electrical measurement variable, such as at least one electrical measurement device selected from the group consisting of: a voltage measurement device, a current measurement device, a potentiostat. Other measurement devices are feasible. The field-effect transistor specifically may not be part of the electrochemical measurement device. Thus, in other words, the analyte detector may comprise the field-effect transistor and the electrochemical measurement device as separate devices, consisting of separate components, except for the multipurpose electrode, which may be part of both the field-effect transistor and of the electrochemical measurement device. Thus, generally, the field-effect transistor and the electrochemical measurement device may form separate components of the analyte detector, except for the multipurpose electrode, which may form part of both the field-effect transistor and the electrochemical measurement device. Specifically, the transistor measurement by using the field-effect transistor and the electrochemical measurement by using the electrochemical measurement device may be distinct and separate measurements. The electrochemical measurement may be made without making use of the field-effect transistor.
The electrochemical measurement and/or the field-effect transistor-based measurement may take place in the presence of at least two different species of biorecognition molecules, for instance at least two different species of receptor molecules, namely at least one first receptor molecule and at least one secondary receptor molecule. The first receptor molecule and the secondary receptor molecule may be able to bind the analyte directly or indirectly. The first receptor molecule and the secondary receptor molecule may bind the analyte simultaneously. The secondary receptor molecule may enhance the electrochemical measurement and/or the field-effect transistor-based measurement, for instance by enhancing a signal and/or a selectivity of the electrochemical measurement and/or of the field-effect transistor-based measurement. The secondary receptor may enhance the signal and/or the selectivity on its own. Additionally, or alternatively, the secondary receptor may be labelled with at least one additional molecule, such as but not limited to an enzyme. The secondary receptor may affect or enhance the detection of the analyte by the analyte detector through an interaction with the analyte, e.g., through binding the analyte. The direct or indirect interaction of the secondary receptor with the analyte may affect or enhance the electrochemical measurement and/or the field-effect transistor-based measurement for instance by affecting or enhancing or producing a change in a concentration of a chemical species, such as but not limited to protons and/or electrons. The change in a concentration of a chemical species may correspond to a concentration of the analyte in the fluid sample. Thus, the secondary receptor may contribute to a signal enhancement of the analyte detector.
As outlined above, the electrochemical measurement device is configured for performing the at least one electrochemical measurement by using the at least one multipurpose electrode. Thus, the multipurpose electrode takes part in the electrochemical measurement. As an example, the at least one multipurpose electrode may be in electrical contact with the electrochemical measurement device, such as with the at least one electrical source and/or the at least one electrical measurement device discussed above. The at least one multipurpose electrode may be part of the at least one electrochemical measurement device and/or may be connected to the electrochemical measurement device, such as via at least one electrical connecting element, e.g., via at least one lead.
The multipurpose electrode may be in electrical contact with a gate electrode of the field-effect transistor. In particular, the gate electrode may be in direct or indirect physical contact with at least one channel of the field-effect transistor, specifically with at least one semiconducting layer. There may, for example, be a dielectric layer between the gate electrode and the channel, for instance to avoid leak current. In the case of a liquid-gated field-effect transistor, an ionic double layer may constitute the dielectric layer. In the embodiments just described, the gate electrode is typically in indirect physical contact with the channel of the field-effect transistor, specifically with the at least one semiconducting layer.
The multipurpose electrode may be at least partially identical with at least one element selected from the group of the gate electrode of the field-effect transistor and the channel of the field-effect transistor. The field-effect transistor may comprise at least one channel. Specifically, the at least one channel may be fully or partially made of at least one semiconducting material. A complete field-effect transistor typically comprises a semiconducting channel, metal source, drain and gate electrodes. Specifically, the gate electrode may be replaced by a reference electrode in solution or by a pseudoreference electrode, such as a metal electrode in solution. The semiconducting layer may comprise at least one material selected from the group consisting of: inorganic elemental semiconductors, inorganic compound semiconductors, and organic semiconductors. Specifically, the semiconducting layer may comprise at least one material selected from the group consisting of: graphene, a layered semiconductor, carbon nanotubes, and semiconducting nanowires. Further, the semiconducting layer may comprise at least one surface accessible to the analyte. In particular, the at least one surface accessible to the analyte may be functionalized by metal particles, specifically be metal particles comprising one or more metals selected from the group consisting of: gold and platinum. However, the use of other metals or alloys is also feasible.
The analyte detector may comprise at least one graphene layer interconnecting at least two electrically conductive electrodes, wherein the graphene layer may be accessible to the analyte, wherein the multipurpose electrode may comprise at least one element of the group consisting of: at least one of the at least two electrically conductive electrodes, the graphene layer. As an example, the semiconducting layer comprising, for instance, graphene may be the multipurpose electrode or may be part of the multipurpose electrode. In particular, the graphene layer may be the multipurpose electrode or may be part of the multipurpose electrode. In such an embodiment at least one other electrode, specifically the source and/or the drain electrode, may serve to make contact to the semiconducting layer comprising, for instance to the graphene layer. The graphene layer may be at least partially covered by metal particles, specifically by gold particles.
The at least one multipurpose electrode may be in electrical contact with one or both of a source electrode or a drain electrode of the field-effect transistor. The multipurpose electrode may, for example, comprise the channel of the field-effect transistor. In this embodiment the source electrode and the drain electrode may serve to make contact to the multipurpose electrode. Alternatively, the multipurpose electrode may be fully of partially identical to one or more of: the source electrode; the drain electrode; the gate electrode.
The analyte detector may comprise at least one further electrode exposable to the fluid sample. The at least one further electrode may comprise at least one electrode selected from the group consisting of a counter electrode and a reference electrode, wherein the electrochemical measurement device is configured for performing the at least one electrochemical measurement using the multipurpose electrode and the further electrode. The analyte detector may comprise at least three electrodes exposable to the fluid sample, wherein at least one of the at least three electrodes may be the multipurpose electrode. The multipurpose electrode may comprise gold. In particular, the analyte detector may comprise at least three electrodes, wherein all three electrodes may be gold electrodes. The multipurpose electrode may comprise at least one functional component exposed to its surface, wherein the at least one functional component may be configured for directly or indirectly interacting with the analyte. Further, the functional component may comprise at least one receptor compound, the receptor compound being capable of binding the at least one analyte. Specifically, the receptor compound being capable of binding the at least one analyte may be selected from the group consisting of: antibodies and fragments thereof, aptamers, peptides, enzymes, nucleic acids, receptor proteins or binding domains thereof and hydrophilic polymers capable of mediating a salting-out effect.
In particular, the at least one electrochemical measurement may comprise at least one measurement selected from the group consisting of: a cyclic voltammetry measurement; an impedance measurement; a potentiostatic measurement; an amperometric measurement; an electrochemical impedance spectroscopy; voltammetry; amperometry; potentiometry; coulometry. As used herein, the term “electrochemical impedance spectroscopy” may generally refer to the measurement of an impedance between the working electrode and the counter electrode as a function of a frequency of an electrical signal applied, such as a voltage and/or current. As further used herein, the term “voltammetry” may generally refer to the measurement of the current between the working electrode and the counter electrode as a function of the voltage applied. As used herein, the term “amperometry” may generally refer to the measurement of the current between working electrode and reference electrode, e.g., as a function of voltage. As used herein, the term “potentiometry” may generally refer to the measurement of the potential difference between the working electrode and the reference electrode. As used herein, the term “coulometry” may generally refer to the determination of the amount of charge produced or consumed during electrolysis. This may, for instance, be done by the measurement of a current between two electrodes, e.g., as a function of time.
Further, the at least one electrochemical measurement device may comprise at least one device selected from the group consisting of: a voltage source, a current source, a voltage meter, a current meter, an impedance meter, an impedance spectrometer, a frequency analyzer, a potentiostat, a frequency generator.
Furthermore, the electrochemical measurement device may be configured for measuring one or more of the following: an absolute value of an impedance between at least two electrodes of the analyte detector as a function of frequency and voltage applied, at least one of the electrodes being the multipurpose electrode; a real part of an impedance between at least two electrodes of the analyte detector as a function of frequency and voltage applied, at least one of the electrodes being the multipurpose electrode; an imaginary part of an impedance between at least two electrodes of the analyte detector as a function of frequency and voltage applied, at least one of the electrodes being the multipurpose electrode; a phase shift between a signal applied to at least one first electrode of the analyte detector and a signal response of at least one second electrode of the analyte detector, at least one of the first and second electrodes being the multipurpose electrode; an electrical current through the multipurpose electrode as a function of a periodic voltage applied to the multipurpose electrode; an electrostatic potential of the multipurpose electrode; an electrical current through the multipurpose electrode; and a voltage between the multipurpose electrode and at least one further electrode, specifically at least one counter electrode and/or at least one reference electrode.
The analyte detector may further comprise at least one controller, wherein the controller may be connected to the field-effect transistor and to the electrochemical measurement device and wherein the controller may be configured for controlling at least one transistor measurement by using the field-effect transistor and for controlling the at least one electrochemical measurement by using the electrochemical measurement device. In particular, the controller may be configured for controlling the at least one transistor measurement by measuring a drain current of the transistor. Furthermore, the controller may be configured for sequentially triggering at least one measurement using the field-effect transistor and the at least one electrochemical measurement. The controller may also be configured for repeatedly performing a sequence of the at least one measurement using the field-effect transistor and the at least one electrochemical measurement.
The analyte detector may further comprise at least one fluid channel, wherein the at least one multipurpose electrode may be disposed to be in contact with the fluid sample within the fluid channel. The fluid channel may comprise at least one fluid inlet for providing the at least one fluid sample to the fluid channel and at least one fluid outlet for disposal of the fluid sample from the fluid channel. In particular, the analyte detector further may comprise at least one external reference electrode being in fluid contact with the fluid channel, specifically at least one Ag/AgCl reference electrode.
The at least one multipurpose electrode may be at least partially covered by a membrane which may be permeable by the analyte. In particular, the membrane may be a polymer membrane. Further, a space in between the membrane and the at least one multipurpose electrode may be at least partially filled by an electrolyte, for example a hydrogel electrolyte.
The at least one transistor may be selected from the group consisting of: an ion-sensitive field-effect transistor (ISFET); a chemically sensitive field-effect transistor (ChemFET); a biological field-effect transistor (BioFET); an enzyme field-effect transistor (ENFET); an extended-gate field-effect transistor (EGFET); a solution-, electrolyte-, water-, or liquid-gated FET.
In accordance with another embodiment, a method for detecting at least one analyte in a fluid sample is disclosed. With respect to definitions and embodiments of the method, reference can be made to definitions and embodiments of the analyte detector described above. The method comprises the following steps:
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- a) providing at least one multipurpose electrode;
- b) providing the at least one fluid sample in contact with the multipurpose electrode;
- c) performing at least one transistor measurement by using at least one field-effect transistor in electrical contact with the multipurpose electrode; and
- d) performing at least one electrochemical measurement by using the multipurpose electrode.
In particular, the method may comprise using an analyte detector as described above or as will be further described below. Thus, as outlined above, specifically, the transistor measurement and the electrochemical measurement may be distinct and separate measurements. Specifically, the electrochemical measurement may be made without making use of the field-effect transistor. Specifically, the transistor measurement using the field-effect transistor and the electrochemical measurement, e.g., using the electrochemical measurement device, may be triggered sequentially, e.g., by using the controller. A sequence of the at least one transistor measurement using the field-effect transistor and the at least one electrochemical measurement may be repeatedly performed, e.g., by the controller.
In method step c) at least one transistor measurement value may be generated. Further, in method step d) at least one electrochemical measurement value may be generated. Specifically, the transistor measurement value and electrochemical measurement value may be combined for one or both of quantitatively or qualitatively detecting the at least one analyte in the fluid sample. Furthermore, method step d) may comprise at least one measurement selected from the group consisting of: a voltammetry measurement; an impedance measurement; a potentiostatic measurement; an amperometric measurement; a coulometric measurement.
In accordance with yet another embodiment of the disclosure, a use of the analyte detector as described above or as will be further described below for the qualitative and/or quantitative determination of the at least one analyte in a fluid is disclosed. In particular, said fluid may be selected from the group of fluids consisting of: body fluids, liquid or dissolved environmental samples and solutions of mixtures of chemical compounds. Specifically, said qualitative and/or quantitative determination of the at least one analyte in a fluid may be involved in diagnostic purposes, environmental control, food safety, quality control or manufacturing processes.
The disclosure further provides and proposes a computer program including computer-executable instructions for performing the method according to the present disclosure in one or more of the embodiments enclosed herein when the program is executed on a computer or computer network. Specifically, the computer program may be stored on a computer-readable data carrier. Thus, specifically, one, more than one or even all of method steps c) and d) as indicated above may be performed and/or controlled and/or evaluated by using a computer or a computer network, typically by using a computer program.
The disclosure further provides and proposes a computer program product having program code means, in order to perform the method according to the present disclosure in one or more of the embodiments enclosed herein when the program is executed on a computer or computer network. Specifically, the program code means may be stored on a computer-readable data carrier.
Further, the disclosure provides and proposes a data carrier having a data structure stored thereon, which, after loading into a computer or computer network, such as into a working memory or main memory of the computer or computer network, may execute the method according to one or more of the embodiments disclosed herein.
The disclosure further provides and proposes a computer program product with program code means stored on a machine-readable carrier, in order to perform the method according to one or more of the embodiments disclosed herein, when the program is executed on a computer or computer network. As used herein, a computer program product refers to the program as a tradable product. The product may generally exist in an arbitrary format, such as in a paper format, or on a computer-readable data carrier. Specifically, the computer program product may be distributed over a data network.
Finally, the disclosure provides and proposes a modulated data signal which contains instructions readable by a computer system or computer network, for performing the method according to one or more of the embodiments disclosed herein.
Typically, referring to the computer-implemented aspects of the disclosure, one or more of the method steps or even all of the method steps of the method according to one or more of the embodiments disclosed herein may be performed by using a computer or computer network. Thus, generally, any of the method steps including provision and/or manipulation of data may be performed by using a computer or computer network. Generally, these method steps may include any of the method steps, typically except for method steps requiring manual work, such as providing the samples and/or certain aspects of performing the actual measurements.
Specifically, the present disclosure further provides:
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- A computer or computer network comprising at least one processor, wherein the processor is adapted to perform the method according to one of the embodiments described in this description;
- a computer loadable data structure that is adapted to perform the method according to one of the embodiments described in this description while the data structure is being executed on a computer;
- a computer program, wherein the computer program is adapted to perform the method according to one of the embodiments described in this description while the program is being executed on a computer;
- a computer program comprising program means for performing the method according to one of the embodiments described in this description while the computer program is being executed on a computer or on a computer network;
- a computer program comprising program means according to the preceding embodiment, wherein the program means are stored on a storage medium readable to a computer;
- a storage medium, wherein a data structure is stored on the storage medium and wherein the data structure is adapted to perform the method according to one of the embodiments described in this description after having been loaded into a main and/or working storage of a computer or of a computer network; and
- a computer program product having program code means, wherein the program code means can be stored or are stored on a storage medium, for performing the method according to one of the embodiments described in this description, if the program code means are executed on a computer or on a computer network.
The analyte detector, the use of the analyte detector and the method for detecting at least one analyte in at least one fluid sample according to the present disclosure presents a variety of advantages over prior art analyte detectors, their use and methods for detecting at least one analyte in at least one fluid sample. Thus, the analyte detector may employ the multipurpose electrode for detecting one and the same analyte via both the transistor-based measurement using the FET and the electrochemical measurement using the electrochemical measurement device. Herein, a measurement range and/or a range of detection may vary between the transistor-based measurement and the electrochemical measurement. Thus, the ability to detect the analyte via the multi-purpose electrode with one transistor-based and one electrochemical method may enhance the measurement range of the analyte detector. Specifically, the measurement range of the analyte detector may thus be enhanced by one or even several orders of magnitude. Generally, the present disclosure thus may allow for providing a single device or analyte detector which combines at least two principles of measurement in one and the same device and which may have an extended measurement range over conventional devices providing only one of these principles of measurement.
Furthermore, the ability to detect the analyte via the multipurpose electrode with one transistor-based and one electrochemical method may increase a measurement accuracy of the analyte detector. Specifically, a measurement range and/or a range of detection of the transistor-based and the electrochemical method may at least partially overlap. Thus, an averaging of detection results of the analyte by the analyte detector in at least parts of the overlapping detection ranges may increase a measurement accuracy of the analyte detector. Further, the provision of at least two different measurement methods with at least partially overlapping measuring ranges in one and the same device, i.e., the analyte detector, may serve as a fail-safe and/or back-up mechanism and thus increase reliability of the analyte detector.
Summarizing the findings of the present disclosure, the following embodiments are typical:
EMBODIMENT 1An analyte detector for detecting at least one analyte in at least one fluid sample, the analyte detector comprising at least one multipurpose electrode exposable to the fluid sample, the analyte detector further comprising at least one field-effect transistor in electrical contact with the at least one multipurpose electrode, the analyte detector further comprising at least one electrochemical measurement device configured for performing at least one electrochemical measurement using the multipurpose electrode.
EMBODIMENT 2The analyte detector according to the preceding embodiment, wherein the multi-purpose electrode is in electrical contact with a gate electrode of the field-effect transistor.
EMBODIMENT 3The analyte detector according to the preceding embodiment, wherein the gate electrode is in direct or indirect physical contact with at least one channel of the field-effect transistor, specifically with at least one semiconducting layer.
EMBODIMENT 4The analyte detector according to any one of the preceding embodiments, wherein the multipurpose electrode is at least partially identical with at least one element selected from the group consisting of the gate electrode of the field-effect transistor and a channel of the field-effect transistor.
EMBODIMENT 5The analyte detector according to any one of the preceding embodiments, wherein the field-effect transistor comprises at least one channel, specifically at least one channel fully or partially made of at least one semiconducting material.
EMBODIMENT 6The analyte detector according to the preceding embodiment, wherein the semiconducting material comprises at least one material selected from the group consisting of: inorganic elemental semiconductors, inorganic compound semiconductors and organic semiconductors, specifically at least one material selected from the group consisting of: graphene; a layered semiconductor; carbon nanotubes and semiconducting nanowires.
EMBODIMENT 7The analyte detector according to any one of the two preceding embodiments, wherein the semiconducting material comprises at least one surface accessible to the analyte, wherein the at least one surface is functionalized by metal particles, specifically by metal particles comprising one or more metals selected from the group consisting of: gold and platinum.
EMBODIMENT 8The analyte detector according to any one of the preceding embodiments, wherein the analyte detector comprises at least one graphene layer interconnecting at least two electrically conductive electrodes, wherein the graphene layer is accessible to the analyte, wherein the multipurpose electrode comprises at least one element of the group consisting of: at least one of the at least two electrically conductive electrodes, the graphene layer.
EMBODIMENT 9The analyte detector according to the preceding embodiment, wherein the graphene layer is partially covered by metal particles, specifically by metal nano particles, more specifically gold nano particles.
EMBODIMENT 10The analyte detector according to any one of the preceding embodiments, wherein the at least one multipurpose electrode is in electrical contact with one or both of a source electrode or a drain electrode of the field-effect transistor.
EMBODIMENT 11The analyte detector according to any one of the preceding embodiments, wherein the analyte detector comprises at least one further electrode exposable to the fluid sample, the at least one further electrode comprising at least one electrode selected from the group consisting of a counter electrode and a reference electrode, wherein the electrochemical measurement device is configured for performing the at least one electrochemical measurement using the multipurpose electrode and the further electrode.
EMBODIMENT 12The analyte detector according to any one of the preceding embodiments, wherein the analyte detector comprises at least three electrodes exposable to the fluid sample, wherein at least one of the at least three electrodes is the multipurpose electrode.
EMBODIMENT 13The analyte detector according to any one of the preceding embodiments, wherein the multipurpose electrode comprises gold.
EMBODIMENT 14The analyte detector according to the preceding embodiment, wherein all three electrodes are gold electrodes.
EMBODIMENT 15The analyte detector according to any one of the preceding embodiments, wherein the multipurpose electrode comprises at least one functional component exposed to its surface, wherein the at least one functional component is configured for interacting with the analyte.
EMBODIMENT 16The analyte detector according to the preceding embodiment, wherein the functional component comprises at least one receptor compound, the receptor compound being capable of binding the at least one analyte.
EMBODIMENT 17The analyte detector according to the preceding embodiment, wherein the receptor compound being capable of binding the at least one analyte is selected from the group consisting of: antibodies and fragments thereof, aptamers, peptides, enzymes, nucleic acids, receptor proteins or binding domains thereof and hydrophilic polymers capable of mediating a salting-out effect.
EMBODIMENT 18The analyte detector according to any one of the preceding embodiments, wherein the at least one electrochemical measurement comprises at least one measurement selected from the group consisting of: a cyclic voltammetry measurement; an impedance measurement; a potentiostatic measurement; an amperometric measurement; electrochemical impedance spectroscopy; voltammetry; amperometry; potentiometry; coulometry.
EMBODIMENT 19The analyte detector according to any one of the preceding embodiments, wherein the at least one electrochemical measurement device comprises at least one device selected from the group consisting of: a voltage source, a current source, a voltage meter, a current meter, an impedance meter, an impedance spectrometer, a frequency analyzer, a potentiostat, a frequency generator.
EMBODIMENT 20The analyte detector according to any one of the preceding embodiments, wherein the electrochemical measurement device is configured for measuring one or more of the following:
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- an absolute value of an impedance between at least two electrodes of the analyte detector as a function of frequency and voltage applied, at least one of the electrodes being the multipurpose electrode;
- a real part of an impedance between at least two electrodes of the analyte detector as a function of frequency and voltage applied, at least one of the electrodes being the multipurpose electrode;
- an imaginary part of an impedance between at least two electrodes of the analyte detector as a function of frequency and voltage applied, at least one of the electrodes being the multipurpose electrode;
- a phase shift between a signal applied to at least one first electrode of the analyte detector and a signal response of at least one second electrode of the analyte detector, at least one of the first and second electrodes being the multipurpose electrode;
- an electrical current through the multipurpose electrode as a function of a periodic voltage applied to the multipurpose electrode;
- an electrostatic potential of the multipurpose electrode;
- an electrical current through the multipurpose electrode;
- a voltage between the multipurpose electrode and at least one further electrode, specifically at least one counter electrode and/or at least one reference electrode.
The analyte detector according to any one of the preceding embodiments, wherein the analyte detector further comprises at least one controller, wherein the controller is connected to the field-effect transistor and to the electrochemical measurement device and wherein the controller is configured for controlling at least one transistor measurement by using the field-effect transistor and for controlling the at least one electrochemical measurement by using the electrochemical measurement device.
EMBODIMENT 22The analyte detector according to the preceding embodiment, wherein the controller is configured for controlling the at least one transistor measurement by measuring a drain current of the transistor.
EMBODIMENT 23The analyte detector according to any one of the two preceding embodiments, wherein the controller is configured for sequentially triggering at least one measurement using the field-effect transistor and the at least one electrochemical measurement.
EMBODIMENT 24The analyte detector according to the preceding embodiment, wherein the controller is configured for repeatedly performing a sequence of the at least one measurement using the field-effect transistor and the at least one electrochemical measurement.
EMBODIMENT 25The analyte detector according to any one of the preceding embodiments, wherein the analyte detector further comprises at least one fluid channel, wherein the at least one multipurpose electrode is disposed to be in contact with the fluid sample within the fluid channel.
EMBODIMENT 26The analyte detector according to the preceding embodiment, wherein the fluid channel comprises at least one fluid inlet for providing the at least one fluid sample to the fluid channel and at least one fluid outlet for disposal of the fluid sample from the fluid channel.
EMBODIMENT 27The analyte detector according to any one of the two preceding embodiments, wherein the analyte detector further comprises at least one external reference electrode being in fluid contact with the fluid channel, specifically at least one Ag/AgCl reference electrode.
EMBODIMENT 28The analyte detector according to any one of the preceding embodiments, wherein the at least one multipurpose electrode is at least partially covered by a membrane which is permeable by the analyte.
EMBODIMENT 29The analyte detector according to the preceding embodiment, wherein the membrane is a polymer membrane.
EMBODIMENT 30The analyte detector according to any one of the two preceding embodiments, wherein a space in between the membrane and the at least one multipurpose electrode is at least partially filled by an electrolyte, for example a hydrogel electrolyte.
EMBODIMENT 31The analyte detector according to any one of the preceding embodiments, wherein the at least one field-effect transistor is selected from the group consisting of: an ion-sensitive field-effect transistor (ISFET); a chemically sensitive field-effect transistor (ChemFET); a biological field-effect transistor (BioFET), an enzyme field-effect transistor (EN-FET); an extended-gate field-effect transistor (EGFET); a solution-, electrolyte-, water- or liquid-gated FET.
EMBODIMENT 32A method for detecting at least one analyte in at least one fluid sample, the method comprising the following steps:
-
- a) providing at least one multipurpose electrode;
- b) providing the at least one fluid sample in contact with the multipurpose electrode;
- c) performing at least one transistor measurement by using at least one field-effect transistor in electrical contact with the multipurpose electrode; and
- d) performing at least one electrochemical measurement by using the multipurpose electrode.
The method according to the preceding embodiment, wherein the method comprises using an analyte detector according to any one of the preceding claims referring to an analyte detector.
EMBODIMENT 34The method according to any one of the preceding method embodiments, wherein in method step c) at least one transistor measurement value is generated, wherein in method step d) at least one electrochemical measurement value is generated, wherein the transistor measurement value and electrochemical measurement value are combined for one or both of quantitatively or qualitatively detecting the at least one analyte in the fluid sample.
EMBODIMENT 35The method according to any one of the preceding method embodiments, wherein step d) comprises at least one measurement selected from the group consisting of: a voltammetry measurement; an impedance measurement; a potentiostatic measurement; an amperometric measurement; a coulometric measurement.
EMBODIMENT 36Use of the analyte detector as defined in any one of the preceding embodiments for the qualitative and/or quantitative determination of the at least one analyte in a fluid.
EMBODIMENT 37The use of the preceding embodiment, wherein said fluid is selected from the group of fluids consisting of: body fluids, liquid or dissolved environmental samples and solutions of mixtures of chemical compounds.
EMBODIMENT 38The use of any one of the preceding embodiments of use, wherein said the qualitative and/or quantitative determination of the at least one analyte in a fluid is involved in diagnostic purposes, environmental control, food safety, quality control or manufacturing processes.
Further optional features and embodiments of the disclosure will be provided in more detail in the subsequent description of typical embodiments, typically in conjunction with the dependent claims. Therein, the respective optional features may be realized in an isolated fashion as well as in any arbitrary feasible combination, as the skilled person will realize. The scope of the disclosure is not restricted by the typical embodiments. The embodiments are schematically depicted in the Figures. Therein, identical reference numbers in these Figures refer to identical or functionally comparable elements.
The analyte detector 110 may further comprise at least one controller 117. The controller 117 may be connected to the field-effect transistor 114 and to the electrochemical measurement device 116 and may be configured for controlling at least one transistor measurement by using the field-effect transistor 114 and for controlling at least one electrochemical measurement by using the electrochemical measurement device 116. The controller 117, as an example, may be or may comprise at least one computer or processor, e.g., for timing and/or triggering the measurements and/or for reading out and/or evaluating measurement results. The controller may further comprise additional elements, such as one or more of a voltage source, a current source, a voltage measurement device, a current measurement device, a frequency generator or the like, as the skilled person will know when designing electrochemical measurements or transistor measurements.
As shown in
The field-effect transistor 114 may be selected from the group consisting of: an ion-sensitive field-effect transistor (ISFET); a chemically sensitive field-effect transistor (ChemFET); a biological field-effect transistor (BioFET); an enzyme field-effect transistor (EN-FET); an extended-gate field-effect transistor (EGFET) 144 as shown in
The channel 126 may be fully or partially made of at least one semiconducting material. Specifically, the channel 126 may comprise at least one semiconducting layer 148, as shown in the liquid-gated FET depicted in
The gate electrode 120 may be in direct or indirect physical contact with the at least one channel 126 of the field-effect transistor 114, as shown in
In
The multipurpose electrode 112 may comprise gold, as shown in
The analyte detector 110 may further comprise a reference electrode 132, in particular an Ag/AgCl electrode. Other combinations are feasible.
The multipurpose electrode 112 may comprise at least one functional component 153 exposed to its surface 155, as shown in
The analyte detector 110 may also be used for an electrochemical measurement, for example for an impedance measurement that may be able to distinguish between the presence of single stranded DNA (graph 160) and absence of single stranded DNA (graph 154) on the gold layer 150 of the multipurpose electrode 112 as can be seen in the measurement diagram 152 in
The analyte detector 110 comprises a field-effect transistor 114. The multipurpose electrode 112 may be at least partially identical with at least one element selected from the group consisting of the gate electrode 120 of the field-effect transistor 114 and the channel 126 of the field-effect transistor 114.
The analyte detector 110 comprises at least one electrochemical measurement device 116 configured for performing at least one electrochemical measurement using the multipurpose electrode 112. The electrochemical measurement device 116 is not depicted in this Figure and may be added in electrical connection to the multipurpose electrode 112. The electrochemical measurement may comprise at least one measurement selected from the group consisting of: a cyclic voltammetry measurement; an impedance measurement; a potentiostatic measurement; an amperometric measurement; an electrochemical impedance spectroscopy; voltammetry; amperometry; potentiometry; coulometry.
The graphene layer 172 may be at least partially covered by metal particles 174, specifically by gold particles 176 as can be seen in
Both field-effect transistor-based measurements and electrochemical measurements may be carried out in the presence of polyethylene glycol (PEG), specifically in the presence of pyrene PEG (P-PEG) and/or thiolated PEG (S-PEG) as shown in the measurement diagrams 152 in
The analyte detector 110 may be able to detect TSH and/or distinguish between different concentrations of TSH via the field-effect transistor-based measurement, as shown in
Herein, CNP stands for charge neutrality point. The shift ΔVCNP depicted in
The analyte detector 110 may also be configured for the analysis of a gaseous analyte. In particular, the analyte detector 110 may be configured for the analysis of at least one blood gas, specifically of CO2.
Glucose concentration may further be determined with a transistor-based measurement by using a multipurpose electrode 112 as described above, wherein the multipurpose electrode 112 may serve as gate electrode 120. In
110 analyte detector
111 fluid sample
112 multipurpose electrode
114 field-effect transistor
116 electrochemical measurement device
117 Controller
120 gate electrode
122 source electrode
124 drain electrode
126 Channel
128 Substrate
130 Surface
132 reference electrode
134 Chamber
136 passivation layer
138 fluid channel
140 fluid inlet
142 fluid outlet
144 extended-gate field-effect transistor
146 extended gate electrode
148 semiconducting layer
150 gold layer
152 measurement diagram
153 functional component
154 bare gold
155 multipurpose electrode surface
156 immobilization of double stranded DNA
158 dehybridization of double stranded DNA
160 presence of single stranded DNA
161 presence of double stranded DNA
162 absence of target DNA
163 presence of target DNA
164 aminothiophenol monolayer
166 anti-TSH antibody
167 thyroid-stimulating hormone (TSH)
168 counter electrode
170 anti-TSH antibody fragments
172 graphene layer
174 metal particles
176 gold particles
178 absence of PEG
180 presence of pyrene PEG
182 presence of thiolated PEG
184 graph relating to the y-axis on the right-hand side
186 graph relating to the y-axis on the left-hand side
188 no TSH
190 10 pM TSH
192 100 pM TSH
194 1 nM TSH
196 10 nM TSH
198 100 nM TSH
199 TSH molecule
200 100 nM BSA
202 100 fM TSH
204 1 pM TSH
206 50 pM TSH
208 1000 pM TSH
210 TSH
212 BSA
214 Membrane
216 Space
218 Electrolyte
220 deionized water
222 8.36 mm Hg
224 20.9 mm Hg
226 41.8 mm Hg
228 83.6 mm Hg
230 209 mm Hg
232 0 minutes of incubation in buffer
234 5 minutes of incubation in buffer
236 10 minutes of incubation in buffer
238 conductive electrolyte solution
240 short bifunctional carboxylated PEG
242 long monofunctional methoxy-terminated PEG
244 buffer without TSH
246 buffer with 0.1 nM
248 buffer with 1 nM TSH
250 buffer with 10 nM TSH
252 buffer with 100 nM TSH
254 buffer without BSH and TSH
256 buffer with 100 nM BSA and without TSH
258 buffer with 100 fM TSH
260 buffer with 1 pM TSH
262 buffer with 50 pM TSH
264 buffer with 100 pM TSH
266 buffer with 1 nM TSH
268 buffer with 100 nM BSA and without TSH
270 buffer with 10 fM TSH
272 buffer with 1 pM TSH
274 buffer with 10 pM TSH
276 buffer with 50 pM TSH
278 buffer with 100 pM TSH
280 buffer with 1 nM TSH
281 buffer with 10 nM TSH
282 first set of transistor-based TSH measurements
284 second set of transistor-based TSH measurements
286 buffer without glucose
288 buffer with 1 mM glucose
290 buffer with 2 mM glucose
292 buffer with 5 mM glucose
294 buffer with 10 mM glucose
296 buffer with 20 mM glucose
298 first set of electrochemical glucose measurements
300 second set of electrochemical glucose measurements
302 first set of transistor-based glucose measurements
304 second set of transistor-based glucose measurement
Claims
1. An analyte detector for detecting at least one analyte in at least one fluid sample, the analyte detector comprising at least one multipurpose electrode exposable to the fluid sample, the analyte detector further comprising at least one field-effect transistor in electrical contact with the at least one multipurpose electrode, the analyte detector further comprising at least one electrochemical measurement device configured for performing at least one electrochemical measurement using the multipurpose electrode, wherein the analyte detector further comprises at least one controller, wherein the controller is connected to the field-effect transistor and to the electrochemical measurement device and wherein the controller is configured for controlling at least one transistor measurement by using the field-effect transistor and wherein the controller additionally is configured for controlling the at least one electrochemical measurement by using the electrochemical measurement device.
2. The analyte detector according to claim 1, wherein the controller is configured for controlling the at least one transistor measurement by measuring a drain current of the field-effect transistor.
3. The analyte detector according to claim 1, wherein the controller is configured for sequentially triggering at least one measurement using the field-effect transistor and the at least one electrochemical measurement.
4. The analyte detector according to claim 3, wherein the controller is configured for repeatedly performing a sequence of the at least one measurement using the field-effect transistor and the at least one electrochemical measurement.
5. The analyte detector according to claim 1, wherein the multipurpose electrode is in electrical contact with a gate electrode of the field-effect transistor.
6. The analyte detector according to claim 1, wherein the multipurpose electrode is at least partially identical with at least one element selected from the group consisting of the gate electrode of the field-effect transistor and a channel of the field-effect transistor.
7. The analyte detector according to claim 1, wherein the analyte detector comprises at least one graphene layer interconnecting at least two electrically conductive electrodes, wherein the graphene layer is accessible to the analyte, wherein the multipurpose electrode comprises at least one element of the group consisting of: at least one of the at least two electrically conductive electrodes, the graphene layer.
8. The analyte detector according to claim 1, wherein the at least one multipurpose electrode is in electrical contact with one or both of a source electrode or a drain electrode of the field-effect transistor.
9. The analyte detector according to claim 1, wherein the analyte detector comprises at least one further electrode exposable to the fluid sample, the at least one further electrode comprising at least one electrode selected from the group consisting of a counter electrode and a reference electrode, wherein the electrochemical measurement device is configured for performing the at least one electrochemical measurement using the multipurpose electrode and the further electrode.
10. The analyte detector according to claim 1, wherein the multipurpose electrode comprises at least one functional component exposed to its surface, wherein the at least one functional component is configured for interacting with the analyte.
11. The analyte detector according to claim 1, wherein the electrochemical measurement device is configured for performing at least one electrochemical measurement selected from the group consisting of: a cyclic voltammetry measurement; an impedance measurement; a potentiostatic measurement; an amperometric measurement; electrochemical impedance spectroscopy; voltammetry; amperometry; potentiometry; coulometry.
12. The analyte detector according to claim 1, wherein the analyte detector further comprises at least one fluid channel, wherein the at least one multipurpose electrode is disposed to be in contact with the fluid sample within the fluid channel.
13. The analyte detector according to claim 1, wherein the at least one multipurpose electrode is at least partially covered by a membrane which is permeable by the analyte.
14. The analyte detector according to claim 1, wherein the at least one field-effect transistor is selected from the group consisting of: an ion-sensitive field-effect transistor (ISFET); a chemically sensitive field-effect transistor (ChemFET); a biological field-effect transistor (BioFET); an enzyme field-effect transistor (ENFET); an extended-gate field-effect transistor (EGFET); a solution- or liquid-gated FET.
15. A method for detecting at least one analyte in at least one fluid sample, the method using the analyte detector according to claim 1, the method comprising the following steps:
- a) providing at least one multipurpose electrode;
- b) providing the at least one fluid sample in contact with the multipurpose electrode;
- c) performing at least one transistor measurement by using at least one field-effect transistor in electrical contact with the at least one multipurpose electrode; and
- d) performing at least one electrochemical measurement by using the multipurpose electrode.
16. The method according to claim 15, wherein in method step c) at least one transistor measurement value is generated, wherein in method step d) at least one electrochemical measurement value is generated, wherein the transistor measurement value and electrochemical measurement value or combined for one or both of quantitatively or qualitatively detecting the at least one analyte in the fluid sample.
17. The analyte detector according to claim 10, wherein the functional component comprises at least one receptor compound, the receptor compound being capable of binding the at least one analyte.
18. The analyte detector according to claim 17, wherein the receptor compound is capable of binding the at least one analyte is selected from the group consisting of: antibodies and fragments thereof, aptamers, peptides, enzymes, nucleic acids, receptor proteins or binding domains thereof and hydrophilic polymers capable of mediating a salting-out effect.
Type: Application
Filed: Aug 21, 2019
Publication Date: Dec 12, 2019
Patent Grant number: 11531003
Applicant: Roche Diagnostics Operations, Inc. (Indianapolis, IN)
Inventor: Alexey Tarasov (Neckargemuend)
Application Number: 16/546,536